New analysis method of the halo phenomenon in finite many-fermion systems. First applications to medium-mass atomic nuclei

A new analysis method to investigate halos in finite many-fermion systems is designed, as existing characterization methods are proven to be incomplete/inaccurate. A decomposition of the internal wave-function of the {$N$-body} system in terms of overlap functions allows a model-independent analysis of medium-range and asymptotic properties of the internal one-body density. The existence of a spatially decorrelated region in the density profile is related to the existence of three typical energy scales in the excitation spectrum of the {$(N-1)$-body} system. A series of model-independent measures, taking the internal density as the only input, are introduced. The new measures allow a quantification of the potential halo in terms of the average number of fermions participating to it and of its impact on the system extension. Those new "halo factors" are validated through simulations and applied to results obtained through energy density functional calculations of medium-mass nuclei. Performing spherical Hartree-Fock-Bogoliubov calculations with state-of-the-art Skyrme plus pairing functionals, a collective halo is predicted in drip-line Cr isotopes, whereas no such effect is seen in Sn isotopes.Comment: 27 Pages, 29 Figures. Accepted for publication in Phys. Rev. C back-to-back with second part (arXiv:0711.1275

Halo phenomenon in finite many-fermion systems. Atom-positron complexes and large-scale study of atomic nuclei

The analysis method proposed in Ref. \cite{rotival07a} is applied to characterize halo properties in finite many-fermion systems. First, the versatility of the method is highlighted by applying it to light and medium-mass nuclei as well as to atom-positron and ion-positronium complexes. Second, the dependence of nuclear halo properties on the characteristics of the energy density functional used in self-consistent Hartree-Fock-Bogoliubov calculations is studied. It is found that (a) the low-density behavior of the pairing functional and the regularization/renormalization scheme must be chosen coherently and with care to provide meaningful predictions, (b) the impact of pairing correlations on halo properties is significant and is the result of two competing effects, (c) the detailed characteristics of the pairing functional has however only little importance, (d) halo properties depend significantly on any ingredient of the energy density functional that influences the location of single-particle levels; i.e. the effective mass, the tensor terms and the saturation density of nuclear matter. The latter dependencies give insights to how experimental data on medium-mass drip-line nuclei can be used in the distant future to constrain some characteristics of the nuclear energy density functional. Last but not least, large scale predictions of halos among all spherical even-even nuclei are performed using specific sets of particle-hole and particle-particle energy functionals. It is shown that halos in the ground state of medium-mass nuclei will only be found at the very limit of neutron stability and for a limited number of elements.Comment: 24 Pages, 32 Figures. Accepted for publication in Phys. Rev. C back-to back with first part (nucl-th/0702050

Structural and chemical requirements for histidine phosphorylation by the chemotaxis kinase CheA

The CheA histidine kinase initiates the signal transduction pathway of bacterial chemotaxis by autophosphorylating a conserved histidine on its phosphotransferase domain (P1). Site-directed mutations of neighboring conserved P1 residues (Glu-67, Lys-48, and His-64) show that a hydrogen-bonding network controls the reactivity of the phospho-accepting His (His-45) in Thermotoga maritima CheA. In particular, the conservative mutation E67Q dramatically reduces phospho-transfer to P1 without significantly affecting the affinity of P1 for the CheA ATP-binding domain. High resolution crystallographic studies revealed that although all mutants disrupt the hydrogen-bonding network to varying degrees, none affect the conformation of His-45. N-15-NMR chemical shift studies instead showed that Glu-67 functions to stabilize the unfavored (NH)-H-delta 1 tautomer of His-45, thereby rendering the N-epsilon 2 imidazole unprotonated and well positioned for accepting the ATP phosphoryl group

Robustness to Algorithmic Singularities and Sensitivity in Computational Kinematics

A robust approach to computational kinematics intended to cope with algorithmic singularities is introduced in this article. The approach is based on the reduction of the original system of equations to a subsystem of bivariate equations, as opposed to the multivariate polynomial reduction leading to the characteristic univariate polynomial. The effectiveness of the approach is illustrated for the exact function-generation synthesis of planar, spherical, and spatial four-bar linkages. Some numerical examples are provided for the case of the spherical four-bar function generator with six precision points to show the benefits of the proposed method with respect to methods reported in the literature.The first author acknowledges the support of Universidad Politecnica de Valencia, research project PAID-00-09. The second author acknowledges the support of McGill University by means of a James McGill Professorship.Gracia Calandin, LI.; Angeles, J. (2011). Robustness to Algorithmic Singularities and Sensitivity in Computational Kinematics. Proceedings of the Institution of Mechanical Engineers part C - Journal of Mechanical Engineering Science. 225(4):987-999. doi:10.1243/09544062JMES2464S9879992254Raghavan, M., & Roth, B. (1993). Inverse Kinematics of the General 6R Manipulator and Related Linkages. Journal of Mechanical Design, 115(3), 502-508. doi:10.1115/1.2919218Lee, H. Y., Woernle, C., & Hiller, M. (1991). A Complete Solution for the Inverse Kinematic Problem of the General 6R Robot Manipulator. Journal of Mechanical Design, 113(4), 481-486. doi:10.1115/1.2912808Innocenti, C., & Parenti-Castelli, V. (1993). Echelon form solution of direct kinematics for the general fully-parallel spherical wrist. Mechanism and Machine Theory, 28(4), 553-561. doi:10.1016/0094-114x(93)90035-tGosselin, C. M., Sefrioui, J., & Richard, M. J. (1994). On the Direct Kinematics of Spherical Three-Degree-of-Freedom Parallel Manipulators of General Architecture. Journal of Mechanical Design, 116(2), 594-598. doi:10.1115/1.2919419Alizade, R. I., & Kilit, Ö. (2005). Analytical synthesis of function generating spherical four-bar mechanism for the five precision points. Mechanism and Machine Theory, 40(7), 863-878. doi:10.1016/j.mechmachtheory.2004.12.010Cervantes-Sánchez, J. J., Gracia, L., Rico-Martínez, J. M., Medellín-Castillo, H. I., & González-Galván, E. J. (2009). A novel and efficient kinematic synthesis approach of the spherical 4R function generator for five and six precision points. Mechanism and Machine Theory, 44(11), 2020-2037. doi:10.1016/j.mechmachtheory.2009.05.006Angeles, J. (2007). Fundamentals of Robotic Mechanical Systems. Mechanical Engineering Series. doi:10.1007/978-0-387-34580-2Bai, S., Hansen, M. R., & Angeles, J. (2009). A robust forward-displacement analysis of spherical parallel robots. Mechanism and Machine Theory, 44(12), 2204-2216. doi:10.1016/j.mechmachtheory.2009.07.005Sommese, A. J., & Wampler, C. W. (2005). The Numerical Solution of Systems of Polynomials Arising in Engineering and Science. doi:10.1142/5763Forsythe, G. E. (1970). Pitfalls in Computation, or why a Math Book isn’t Enough. The American Mathematical Monthly, 77(9), 931. doi:10.2307/2318109Angeles, J., Hommel, G., & Kovács, P. (Eds.). (1993). Computational Kinematics. Solid Mechanics and Its Applications. doi:10.1007/978-94-015-8192-9Yang, A. T., & Freudenstein, F. (1964). Application of Dual-Number Quaternion Algebra to the Analysis of Spatial Mechanisms. Journal of Applied Mechanics, 31(2), 300-308. doi:10.1115/1.3629601Gupta, K. C., & Beloiu, A. S. (1998). Branch and circuit defect elimination in spherical four-bar linkages. Mechanism and Machine Theory, 33(5), 491-504. doi:10.1016/s0094-114x(97)00078-

The geological setting of Carboniferous magmatism in the proto-Andean margin of Gondwana, Sierra Pampeanas, Argentina

Fil: Dahlquist, J. A. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Dahlquist, J. A. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones en Ciencias de la Tierra; Argentina.Fil: Basei, M. Universida de de Sao Paulo. Instituto de Geociencias; Brasil.Fil: Alasino, P. H. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Alasino, P. H. Universidad Nacional de la Rioja. INGeReN-CENIIT; Argentina.Fil: Alasino, P. H. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentina.Fil: Campos, M. Universidade de Sao Paulo. Instituto de Geociencias; Brasil.Fil: Casquet, C. Universidad Complutense. Departamento de Petrología y Geoquímica; España.Our petrogenetic understanding of the Carboniferous granites of the Sierras Pampeanas has improved in recent years, but their geodynamic setting is still not well constrained. Domeier and Torsvik (2014) affirm that there is no documented and unambiguous evidence of an active margin in the proto-Andean margin of Gondwana before the late Carboniferous (~ 320 Ma).Fil: Dahlquist, J. A. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Dahlquist, J. A. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones en Ciencias de la Tierra; Argentina.Fil: Basei, M. Universida de de Sao Paulo. Instituto de Geociencias; Brasil.Fil: Alasino, P. H. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Alasino, P. H. Universidad Nacional de la Rioja. INGeReN-CENIIT; Argentina.Fil: Alasino, P. H. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentina.Fil: Campos, M. Universidade de Sao Paulo. Instituto de Geociencias; Brasil.Fil: Casquet, C. Universidad Complutense. Departamento de Petrología y Geoquímica; España.Geoquímica y Geofísic

Extensive collection of femtoliter pad secretion droplets in beetle Leptinotarsa decemlineata allows nanoliter microrheology

Pads of beetles are covered with long, deformable setae, each ending in a micrometric terminal plate coated with secretory fluid. It was recently shown that the layer of the pad secretion covering the terminal plates is responsible for the generation of strong attractive forces. However, less is known about the fluid itself because it is produced in extremely small quantity. We here present a first experimental investigation of the rheological properties of the pad secretion in the Colorado potato beetle {\it Leptinotarsa decemlineata}. Because the secretion is produced in an extremely small amount at the level of the terminal plate, we first develop a procedure based on capillary effects to collect the secretion. We then manage to incorporate micrometric beads, initially in the form of a dry powder, and record their thermal motion to determine the mechanical properties of the surrounding medium. We achieve such a quantitative measurement within the collected volume, much smaller than the $1 {\rm \mu}$l sample volume usually required for this technique. Surprisingly, the beetle secretion was found to behave as a purely viscous liquid, of high viscosity. This suggests that no specific complex fluid behaviour is needed during beetle locomotion. We build a scenario for the contact formation between the spatula at the setal tip and a substrate, during the insect walk. We show that the attachment dynamics of the insect pad computed from the high measured viscosity is in good agreement with observed insect pace. We finally discuss the consequences of the secretion viscosity on the insect adhesion

The moderating effect of brand orientation on inter-firm market orientation and performance

While prior research has shown that market and brand orientation are key contributors to successful business performance, research to date has not fully explored how inter firm collaboration for these two key orientations can enhance business performance. The purpose of the paper is to investigate the relationship between inter-firm market and performance; to test for the moderating role of brand orientation in that relationship. A total of 169 completed pairs of surveys were collected of small and medium enterprises operating internationally in a variety of industries in Switzerland. The results show that inter-firm market and brand orientation are two antecedents of marketing and financial performance. The impact of inter-firm market on marketing and financial performance is significant when the brand orientation is favorable. This study extends previous research by examining the moderating role of brand orientation on inter firm market orientation, which is important, especially for firms wanting to increase their brand reputation by entering into partnerships with other firms. Further research is indicated, to identify the key moderators of the driving force of inter-firm market in relation to business performance and the reason why maintaining a strong brand presence is important in the international marketplace

Sr, C and O isotope composition of marbles from the Sierra de de Ancasti, Eastern Sierras Pampeanas, Argentina: age and constraints for the Neoproterozoic–Lower Paleozoic evolution of the proto-Gondwana margin

The Sierra Brava Complex on the eastern flank of the Sierra de Ancasti consists of marbles, metabasites, calc-silicate rocks, psammo-pelitic schists and gneisses. In the central part of this sierra a thick succession of banded schists (Ancasti Formation) crops out. Regional metamorphism of these rocks is attributed to the Famatinian orogeny (Ordovician), metamorphic grade increasing westwards and southwards and culminating in a migmatite complex on the western side of the Sierra. The meta-carbonate rocks are subdivided into a northeastern group (low-grade calcite marbles), and a southeastern group (high-grade calcite and calcite-dolomite marbles). Twenty-three marble samples were analysed for Sr isotope composition and Rb, Mn, Mg and Ca contents, and six for C and O isotope composition. An Ediacaran depositional age of 570 –590Ma is inferred by reference to the trend of 87Sr/86Sr in Neoproterozoic seawater. Thus the metacarbonates are probably slightly older than the Ancasti Formation (equivalent to the Puncoviscana Formation of northern Argentina), which has a maximum sedimentation age of ca. 570Ma. Ediacaran depositional ages have also been reported for metacarbonates elsewhere in Argentina, Uruguay and Brazil. We propose that the Sierra de Ancasti carbonates on one hand, and those in the Western Sierras Pampeanas (Difunta Correa Sequence) and –tentativelythe Corumbá Group of Brazil on the other, represent platforms on opposite margins of the extinct Clymene Ocean, whereas Neoproterozoic carbonate successions such as the Loma Negra Formation (Tandilia, southern Argentina) and the Arroyo del Soldado Group (Uruguay) were deposited on the eastern side (present coordinates) of the Rio de la Plata craton, which at the time occupied a position farther to the north.Peer reviewe